Inhaler mechanism

ABSTRACT

A dosing device comprising a dispensing means for dispensing a dose material, and a dose actuation mechanism, in which the dose actuation mechanism comprises a readily deflectable member, and a cascade of at least two pivoted elements, movement of one causing movement of the other, wherein the deflectable member is moveable by the user, and its movement is transferred to the first of the cascade of pivoted elements, so as to actuate the dispensing means. A first biasing means communicates with one pivoted element so that as movement is transferred between the pivoted elements, energy stored in the first biasing means is released to increase the force associated with the movement. A dose actuating mechanism for use in a dosing inhaler is also provided.

FIELD OF THE INVENTION

This invention concerns a dosing device and in particular relates todosing devices for drug delivery such as injectors and inhalers, and amechanism for use in such devices.

BACKGROUND OF THE INVENTION

In treatment for asthma and other respiratory problems, a patient maytake medication into his lungs by inhaling either an aerosol mist or acloud of fine particles from an inhaler. Conventional asthma inhalersfall into two categories: ‘dry powder inhalers’ and ‘metered doseinhalers’ (MDI's).

Breath operated MDI's are known. For example U.S. Pat. No. 3565070describes an ‘inhalation actuable aerosol dispenser’ and in addition WO92/09232 and European patent 0147028 disclose further examples of breathoperated MDI'S.

An MDI consists of a small canister containing medication with ametering valve and a valve stem. The MDI delivers a metered dose to thepatient when the valve stem is pressed. The fundamental problem in thedesign of breath operated MDI's is that a large force (of the order of30 N) is required to depress the valve stem and actuate an MDI. Howeveronly a very small force is available from the patient's breath. Thisproblem is partly overcome in the prior art by manually compressing alarge spring to a sufficient force to actuate the device. The spring iscompressed by the patient, either by a positive ‘cocking’ process orautomatically when the patient opens the mouthpiece cover. The spring isthen released by a trigger operated by the patient's breath. Theoperation of the trigger is however difficult to engineer reliably andcheaply since releasing a spring with a stored force of 30N using a lowforce from the patient's breath is a difficult technical challenge.

WO 92/09323 describes a pneumatic system for holding the stored force.This requires a number of components which must be carefullymanufactured to maintain a satisfactory vacuum seal during operation.European patent 0147028 describes a mechanical trigger design whichrequires extremely tight manufacturing tolerances and which to someextent depends on consistent levels of friction for repeatableoperation.

The present invention seeks to provide an inhaler with a dose actuationmechanism which provides a very substantial amplification of the forcebeing available from a patient's breath, whilst not being vulnerable tochanges in the coefficient of friction between moving parts.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a dosing devicecomprising a dispensing means for dispensing a dose material, and a doseactuation mechanism, in which the dose actuation mechanism comprises areadily deflectable member, and a series of at least two movableelements which transmit and magnify movement of the first element in theseries to the last element in the series by a cascade effect, whereinthe deflectable member is movable by airflow, and its movement istransferred to the first element of the said series so as to actuate thedispensing means.

Preferably the moveable elements are pivoted and arranged sequentiallyto inter-communicate, movement of a first pivoted element by thedeflectable member effecting movement of at least another pivotedelement so as to actuate the dispensing means.

The deflectable member is preferably movable in response to inhalationby a patient. Thus in use only inhalation by the patient is required toactivate the dose actuation mechanism and thus cause the measured doseto be dispensed.

The use of a cascade of moveable pivoted elements provides a form ofamplification of the originating force created by the intake of breath,and whilst any number of such elements may be employed in the cascade,in general two such elements are sufficient.

As a preferred feature of the invention, this amplification may beachieved by a first biasing means which communicates with one moveableelement so that as movement is transferred between the moveableelements, energy stored in the first biasing means is released toincrease the force associated with the movement. This ensures that asmall initial force exerted on the deflectable member is increased inmagnitude as it cascades through the moveable elements. In such a way, asmall initial force is magnified to allow actuation of the dispensingmeans.

Preferably one moveable element remote from the deflectable member isattached to, or acts on, the dispensing means so as to restrainactuation thereof until the said moveable element is deflected as aresult of a cascade action. In this way the movement of the deflectablemember and the pivoted elements can be used to release stored energy toprovide sufficient force to dispense a dose from the dispensing means.In particular the dispensing means may be associated with a secondbiasing means, in which energy is stored in compression, which storedenergy is released on movement of a pivoted element.

The invention also lies in a dose actuating mechanism for use in adosing device, comprising a deflectable member and a cascade of at leasttwo moveable elements, movement of the deflectable member beingtransferred to and between the moveable elements, in such a manner as totrigger the release of stored energy sufficient to release a dose.

Preferably the dosing device is also provided with a lid including atleast one cam surface, wherein movement of the lid results in thepivoted elements being restored to positions of unstable equilibriumready to cause actuation of the dispensing means when the cascade istriggered.

The pivoted elements are preferably movable into a first position ofunstable equilibrium, which movement is translated into stored energy,in the second biasing means, and when triggered, move into a secondposition of equilibrium, during which movement the stored energy isreleased from the second biasing means to dispense a dose from thedispensing means.

Preferably the moveable pivoted elements each comprise over-centremechanisms. Thus where the over-centre mechanisms are arrangedsequentially, movement of a first over-centre mechanism in the cascade,triggered by movement of the deflectable member, results in subsequentmovement of the next, and in turn, any subsequent over-centremechanisms, the last of which allows for actuation of the dispensingmeans.

Particularly preferred is the use of a first and a second over-centremechanism as the moveable elements, the first over-centre mechanismcommunicating with first biasing means and the second over-centremechanism communicating, via the dispensing means, with a second biasingmeans.

The use of two over-centre mechanisms in this way provides a forcecascade which eventually results in actuation of the dispensing means.Thus an initial small force produced by movement of air due toinhalation, moves the deflectable member, which movement causes a firstover-centre mechanism to shift over-centre, to produce an increasedintermediate force because of the action of the first biasing means,this intermediate force in turn causes a second over-centre mechanism toshift over-centre to release a larger stored force, typically 30N, froma second biasing means, so as to operate the inhaler. The use ofover-centre mechanisms allows for a very substantial force amplificationwhilst reducing the effect of changes in the co-efficient of frictionbetween moving parts.

The dose actuation mechanism of the present invention is applicable tovarious inhalers where breath actuation is desirable and where the drugis delivered by the release of stored energy in a spring. For examplethere is a family of devices known as pump jets in which the drug isdelivered under pressure through a nozzle by the action of a mechanicalpump, typically a piston pump. These have been used in the past fornasal drug delivery and for perfumes where the droplet size is not ascritical as for inhaled drugs but they are now being developed to thepoint where very small droplets can be produced, suitable forinhalation. The mechanical pump may be driven by a powerful spring whichis released by the patient's inhalation. The present invention issuitable for this type of inhaler either used in the mouth or for nasaldrug delivery.

There are also some types of dry powder inhaler (DPI) in which therelease of the drug particles is assisted by air movement caused by apiston driven by the release of a compressed spring or the drugparticles are mechanically released by the direct action of a triggeredspring. Again there is a need for a trigger mechanism capable of beingreliably triggered by a small force, and thus the present invention isalso applicable for these inhalers.

The present invention is also applicable in other fields where forceamplification is valuable, for example other drug delivery and medicaldevices where stored energy is released by a manually operated trigger.Examples of this are needle-free injection systems (both with liquiddrug and powder) in which the drug is accelerated towards the patient'sskin through the release of stored energy, auto-injectors in which aconventional syringe and needle are actuated by the release of storedenergy and nasal or topical sprays in which the dosing pump is springactuated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example, and withreference to the accompanying drawings in which:

FIG. 1 is a section through a base of a breath operated meter doseinhaler according to the preset invention illustrating a first chamberand a second chamber;

FIG. 2 is a partial sectional view on the line II—II of FIG. 1 showingthe second chamber of the inhaler before a dose has been supplied;

FIG. 3 is a partial sectional view on the line III—III of FIG. 1 showingthe first chamber of the inhaler before a dose has been supplied, lineI—I is the section along which FIG. 1 is taken;

FIG. 4 is a partial sectional view on the line II—II of FIG. 1 after adose has been supplied;

FIG. 5 is a partial sectional view on the line III—III of FIG. 1 after adose has been supplied;

FIG. 6 is a sectional view, to an enlarged scale, on the line II—II ofFIG. 1 illustrating the interaction of linkage components in the secondchamber when delivering a dose;

FIGS. 7 and 8 are a partial sectional view on the line VII—VII of FIG. 1illustrating the positioning of a cam feature during operation of theinhaler;

FIGS. 9 and 10 are a sectional view, to an enlarged scale, on the lineVII—VII of FIG. 1 showing an alternative cam feature;

FIGS. 11 and 12 show alternative arrangements of the link mechanism andtheir interaction when delivering a dose;

FIG. 13 shows a series of views illustrating a dose counter mechanismused with the meter dose inhaler; and

FIG. 14 is a schematic illustration showing individual components of themetered dose inhaler prior to assembly.

Referring to FIGS. 1, 2 and 3, a preferred embodiment of a breathoperated metered dose inhaler (MDI) in accordance with the presentinvention comprises a hollow outer body 10, typically made of plasticsmaterial, which includes a protruding portion 12 with a central aperture14. The protruding portion 12 and aperture 14 form a mouthpiece fromwhich a dose may be inhaled on operation of the MDI. A mouthpiece cover16 is pivotally attached to the outer body 10 and in FIG. 1 themouthpiece cover 16 is shown pivoted away from the body 10 to allowaccess to the mouthpiece.

Internally the body 10 is provided with a supporting platform 18 bearingboss 20. A biasing means 22, such as a spring, is positioned at one endto an inner base wall of body 10 with the other end of the spring 22engaging with a canister 24 which contains the dosing medium. Thecanister 24 is held between the spring 22 and the boss 20 provided onthe supporting platform 18. The canister 24 is provided with a stem 26which connects with a passage 28 within boss 20 providing a nozzle 30through which the dose is emitted.

Two adjacent chambers 32, 34 as shown in FIG. 1 are defined within theouter body 10 by the supporting platform 18 and part of the inner wallof the lower part of outer body 10. Chamber 34 as shown in FIG.3.provides an actuation chamber with two apertures, an inlet aperture 36and an outlet aperture 38, so as to provide an air passage through thefirst chamber 34 over vane 40. An actuation mechanism 42 is contained inthe second chamber 32 shown in FIG. 2 and comprises a shaft 44 which isrotatable and attached to vane 40, over-centre links 46, 48 and abiasing means 50. The shaft 44 is attached to the over-centre link 48 bya push rod 52 with over-centre link 46 being attached at one end to aneck of the canister 24 via a push rod 54 and yoke 56.

In FIGS. 2 and 3, the MDI is shown with the mouthpiece cover 16 openedand is ready for operating to provide a dose. Over-centre link 46 isheld in place by the pressure of the spring 22 acting on canister 24,and thus on push rod 54. The second over-centre link 48 is held in placeby the action of the small 7 spring 50. The vane 40 is shown in FIG. 3and not in FIG. 2 because typically the vane is mounted in a separatecompartment to that containing the over-centre links 46, 48, the shaft44 and push rod 52.

In use, a patient places his mouth over mouthpiece 12, 14 and inhales.This creates a flow of air through the chambers 32, 34, air enteringfrom inlet aperture 36 and passing via aperture 38 into aperture 14 andthus the patient's mouth. The resulting flow of air over the vane 40causes the vane to rotate as shown in FIG. 5 and so apply a compressiveforce to the push rod 52. Providing the air flow has reached apre-determined level which is sufficient to overcome the effect ofspring 50, the second over-centre link 48 moves over-centre as shown inFIG. 4. Thus the effect of the small spring 50 is to drive linkage 48against linkage 46. The relative sizes of the springs 22 and 50 and thegeometry of both the actuating chambers 32, 34 and the general internalbody of the device, are selected to ensure that linkage 46 is drivenover-centre by the action of linkage 48.

FIGS. 4 and 5 show the breath operated MDI after a dose has beenreleased, with corresponding reference numerals to those used in FIGS.1, 2 and 3 having been used for the common features. FIGS. 4 and 5 showhow movement of the vane 40 results in over-centre movement of linkage48 and subsequently linkage 46. The springs 22 and 50 are seen in theirextended unbiased positions, where less energy is stored.

A detailed view of how the mechanism 42 works is given in FIG. 6. FIG.6a) shows the actuation mechanism before inhalation. As inhalationoccurs, a relatively small force, for example of the order of 0.25 N, inrod 52 is sufficient to displace link 48 to the right, even though alarger force, for example 3.5 N, may be stored in spring 50. In FIG.6b), link 48 now has moved to the right and is pressing against link 46.The force of spring 50, which may have reduced to perhaps 2.5N becausethe spring has expanded, is sufficient to displace link 46 to the right,although link 46 is supporting a much greater force of perhaps 30Nthrough pushrod 54. In this way the can 24 is released when themechanism 42 collapses into the final position shown in FIG. 6c).

As linkage 46 is driven over-centre, the restraining force on thecanister 24 due to the force exerted by the push rod 54 is removed andthe spring 22 is free to urge the canister 24 downwards against boss 20,causing a dose to be released through stem 26.

It can be seen that over-centre link 46 exerts a force on the neck ofthe canister 24 so storing compressive energy in the spring 22, andsimilarly over-centre link 48 stores compressive energy in spring 50. Oninhalation, the vane 40 is deflected by a small force from the patientinhaling, and the vane 40 moves linkage 48 releasing the stored energyin spring 50.

This results in a force cascade, the lesser force of inhalation causingan increased intermediate force at the link 48. This intermediate forceis sufficient to deflect link 46, as seen in FIG. 6. As link 46 isdeflected, rod 54 moves away from the neck of container 24, releasingthe stored compressive energy in spring 22 and so providing a furtherincrease in the force. Thus a force of the order of 30N is achieved,which is sufficient to dispense a dose from the stem 26.

After use, the patient closes the mouthpiece cover 16 and therebyreplaces the linkages to their original position. The replacement isachieved by reset link 100 as shown in FIGS. 7 and 8. At one end of thelink there is a slot 102 which engages with one drive pin 104 at thepivot of the mouthpiece cover. At the other end of the reset link 100there are two pins 106, 108 which are positioned underneath the linkagesof the over-centre mechanism 46, 48. A drive pin 110 on the oppositeside of the mouthpiece cover seen in FIG. 3 and FIG. 5 acts against yoke56 to lift the canister and compress spring 22.

FIG. 7 shows the mechanism after the device has been actuated. Theover-centre mechanism is dropped and the reset link 100 is in the lowerposition. The user then closes the mouthpiece cover.

As the mouthpiece cover closes, the two drive pins 104, 110 in themouthpiece cover take effect. Drive pin 110 engages with yoke 56 andlifts the canister 24 upwards, compressing spring 22. Drive pin 104 isengaged in reset link 100 and lifts this link upwards. The two pins 106,108 on the reset link then press on features in the over-centremechanism linkage and return the linkage to an upright position. FIG. 8shows the linkages 46, 48 and the reset link 100 in this position.

The position of the two drive pins 104, 110 in the mouthpiece cover isarranged such that the action of pin 110 is to lift the canister 24first, before pin 104 takes effect and reset link 100 starts to move theover-centre linkage, thus avoiding an over-stressed condition for thelinkages.

When the mouthpiece cover is opened, the process is largely reversed.However the size of slot 102 in the reset link 100 is larger than thediameter of pin 104, thus causing the reset link 100 to remain inposition and retain the over-centre link 46 in an upright position untilcan 24 is lowered in place, then holding the mechanism 42 in position asshown in FIG. 8.

An alternative arrangement for resetting the inhaler mechanism isillustrated in FIG. 9 and 10. In this case, after use, the patientcloses the mouthpiece cover 16, and cam feature 60 inside the cover 16,compress springs 22 and 50 and also returns the linkages 46 and 48 andthe vane 40 to the rest, or cocked position, of FIG. 2. Cam feature 62only acts to compress spring 22 at the same time. FIGS. 9 and 10illustrate the cam profiles for cam 60. Cams 60 and 62 are positioned onopposite sides of cover 16, see FIG. 14. Cam feature 60 is provided onan internal wall of the mouthpiece cover 16, with cam feature 62 beingprovided in the corresponding position on the opposite inner wall of thecover 16, see FIG. 14. The cam features 60, 62 are designed such thatduring storage the smaller plastics components of the actuationmechanism 42 are not held under stress.

The cam 60 is positioned within the outer body 10, adjacent to theactuation mechanism 42. The lower part of the cam 60 has toothedportions 64, 66 and 68 which engage against pegs 70, 72 and 74 whichextend to the side of the linkage mechanisms 46 and 48. In FIG. 9, thelinkage mechanisms are shown dotted for clarity and this Figure showsthe post-triggered condition, i.e. after delivery of a dose.

When the mouthpiece cover 16 is closed as shown in FIG. 10, the cam 60,which is directly attached to the cover 16, rotates clockwise andreturns the over-centre mechanisms, or links, 46 and 48, to theirstarting position as required for operation of the inhaler to produce adose. At the same time a lobe 76 provided on the cam 60 engages on ayoke 78 to lift the canister 24 and so compress the spring 22. Thecorresponding cam 62 provided within the mouthpiece cover 16 has a lobeidentical with lobe 76, but does not have any toothed portions. Bysetting dimensions correctly, toothed portion 68 and lobe 76 hold thestored force from springs 50 and 22 respectively. By this means, therewill be no stress on the linkages 46 and 48 during storage with themouthpiece cover 16 closed.

The action of closing the cover 16 restores compressed energy within thebiasing means so that the breath operated MDI is once again in thepre-triggering position and is capable of providing a single dose oninhalation. Thus the action of closing the cover 16 ensures the breathoperated MDI is primed, priming being achieved by the interaction of thecam surfaces with the pegs and the yoke.

In the present invention, two over-centre mechanisms are used to storeand release energy in the springs 22 and 50. The use of at least twoover-centre mechanisms which can cascade together ensures that a verysmall force, as provided by a patient inhaling, can release anintermediate force stored in an intermediate spring 50 and that theintermediate force can then be used to release a larger stored force,typically 30N, which then operates the inhaler. The use of twoover-centre mechanisms ensures that the inhaling force does not need tobe great and that tight manufacturing tolerances are not required. Thetwo over-centre mechanical linkages can be constructed from a very smallnumber of parts with moulded-in flexible hinges. Thus a breath operatedMDI can be provided with a trigger mechanism which does not requireprecise dimensions for manufacture and which is cost effective.

FIG. 11 shows an alternative arrangement of the link mechanism with anadditional flexing piece 201 between links 52 and 48. This allows thelinkage to be driven with a higher mechanical advantage as follows. FIG.11a) shows the mechanism in the primed position. When the user inhales,the vane pivots around shaft 44 and link 52 presses to the right againstlink 48. When over-centre mechanism 48 collapses to the right, link 201allows link 48 to accelerate away from link 52 as FIG. 11b). Link 48then strikes link 46, causing the device to operate as in FIG. 11c).

The additional link 201 means that the travel required from arm 202 onshaft 44 is less than the travel required from the mechanism shown inFIG. 6. This means that arm 202 is shorter and hence the mechanicaladvantage available to drive the trigger mechanism is greater.

FIG. 12 shows a different alternative arrangement. In this case there isno spring 50. Instead, there is a link 203 bridging the top ofmechanisms 48 and 46 and having a hinged connection to push rod 54. Theeffect of this is that links 48 and 46 are both held in compression bythe compressive force transmitted by push rod 54 as shown in FIG. 12a)with the mechanism primed before triggering. In this position, by way ofexample, the compressive force in push rod 54 may be 30N. If link 203 isconstructed with a 10:1 lever ratio, then the compressive forces inlinks 48 and 46 would be approximately 27N and 2.7N respectively. Thismeans that link 48 can be collapsed by the use of a very low force suchas 0.2 or 0.3 N in push rod 52, as described previously. FIGS. 12b) and12 c) shows the device during-operation.

The benefit of this arrangement is that spring 50 is eliminated whichnot only saves the cost of that component but also reduces the amount ofspace required by the mechanism.

FIG. 13 illustrates operation of a dose counter used with the inhalerand as shown in FIG. 14. The count indication is given by two wheels112, 114. Each wheel comprises a toothed disc portion and a smooth disc,the smooth disc of wheel 112 bearing digits 00 to 20 and wheel 114bearing digits 0 to 9. When the wheels are viewed together throughwindow 116, the display can show any number from 000 to 209. Typicallythe display is used as an indication of doses remaining for the patient,ie the display starts at, for example, 200 and counts down to 000.

Wheel 114 is driven round by the action of flexible lever 118 acting onthe ratchet teeth moulded on the wheel 114. Reverse movement isprevented by the action of sprung pawl 120 acting against the sameratchet teeth.

Lever 118 contains a pin feature 122 which engages with yoke 56. Whenthe inhaler device is actuated and reset, the can 24 moves firstdownwards, then upwards. This action causes lever 118 to move, whichdrives round wheel 114 thereby causing the counter indication to changeby one unit. The design ensures that a count is only made when a dose istaken by the user. In the event of the mouthpiece cover 16 being openedand closed without a dose being taken, the can 24 will not have droppedand therefore the counter will not have been actuated.

The smooth disc of wheel 114 has a single protruding feature 124 whichis designed to engage in teeth moulded into wheel 112. Once perrevolution, this feature will cause wheel 112 to index its position by asingle count. Thus, for example wheel 114 may change from 0 to 9, wheel112 may change from 17 to 16 and the display would change from 170 to169.

Sprung lever 126 is provided to engage in tooth features 128 in wheel112 to provide a ‘detent’ action, retaining the wheel in its correctorientation at all times except when engaged with and driven by thewheel 114.

All the features of the counter are moulded in a single component fromplastics material, thus providing a construction which is very simpleand low cost.

FIG. 14 shows how a breath operated MDI in accordance with the inventioncould be manufactured with the actuation mechanism being composed of fewseparate components. FIG. 12 is an exploded view of a typical breathoperated MDI, comprising an outer body 150, biasing means 22, canister24, a yoke 78 with protruding leg 152, a mouthpiece element 154, biasingmeans 50, an actuating section 158, a lower cap element 160 andmouthpiece cover 16. The actuating section 158 is moulded in one pieceto include both linkages 46 and 48, push rod 52, shaft 44 and vane 40.The making of multiple parts of the actuation mechanism by moulding inplastics material as a one piece actuating section 158 simplifiesassembly of the breath operated MDI and reduces costs. Drive pin feature104 is provided on an internal wall of the mouthpiece cover 16, withdrive pin 110 being provided in the corresponding position on theopposite inner wall of the cover 16.

It will be apparent to a skilled person that the same effect could beachieved by counters of different physical construction including, forexample, concentric indicating wheels or cylindrical indicating wheelswhich might provide different user benefits in terms of the size of thedisplay digits, the size of the counter package and the number ofcomponents.

It will also be apparent to a skilled person in the art that theactuation mechanism 42 as described above may be positioned in variousplaces within the outer body 10, for example above the canister 24,inside the biasing means 22, or alongside the canister 24. The actuationmechanism may also release the main spring 22 by the use of push rods,levers or other links as is readily apparent. The vane 40 could also beindependently positioned elsewhere and linked to the two over-centrelinks by means other than push rod 52. The upper end of linkage 46 couldbe supported by a flexing arm similar to the arm linked to the upper endof linkage 48 and in such a case the connection to canister 24 could beby push rod or other mechanical link.

What is claimed is:
 1. A dosing device comprising dispensing means fordispensing a dose material, a first biasing means engaging with thedispensing means, and a dose actuation mechanism comprises a deflectablemember moveable by airflow, and a series of at least two moveableelements which transmit movement of the first element in the series tothe last element in the series by a cascade effect, such that movementof the deflectable member is transferred to the first element of thesaid series and a second biasing means communicates with one of the atleast two moveable elements so that as movement is transferred betweenthe movable elements, energy stored in the second biasing means isreleased to increase the force associated with the movement of themoveable elements.
 2. A dosing device according to claim 1, wherein themoveable elements are pivoted.
 3. A dosing device according to claim 1,wherein the moveable elements are arranged to inter-communicatesequentially, so as to actuate the dispensing means.
 4. A dosing deviceaccording to claim 1, wherein the deflectable member is movable inresponse to inhalation by a patient.
 5. A dosing device according toclaim 1, wherein one moveable element remote from the deflectable memberis attached to, or acts on, the dispensing means so as to restrainactuation thereof until the said moveable element is deflected as aresult of a cascade action.
 6. A dosing device according to claim 1,further comprising a lid including at least one cam surface, whereinmovement of the lid results in the moveable elements being restored topositions of unstable equilibrium ready to cause actuation of thedispensing means when the cascade is triggered.
 7. A dosing deviceaccording to claim 1, wherein the moveable elements each compriseover-centre mechanisms.
 8. A dosing device according to claim 1, whereinthe moveable elements are a first and a second over-centre mechanism,the first over-centre mechanism communicating with first biasing meansand the second over-centre mechanism communicating, via the dispensingmeans, with a second biasing means.
 9. A dosing device according toclaim 8, wherein parts of the dosing actuation mechanism are moulded asa one piece actuating section with moulded-in flexible hinges.
 10. Adose activating mechanism for use in a dosing inhaler having adispensing means for dispensing a dose material and a first biasingmeans fro engaging with the dispensing means, wherein the mechanismcomprises a deflectable member moveable by airflow, and a cascade of atleast two moveable elements, movement of the deflectable member beingtransferred to and between the moveable elements, wherein a secondbiasing means communicates with one biasing element so that as movementis transferred between the moveable elements, energy stored in thesecond biasing means is released to increase force associated with themovement of the moveable elements.
 11. A dose actuating mechanismaccording to claim 10, wherein each moveable element is pivoted andcomprises an over-centre mechanism.
 12. A dose actuating mechanismaccording to claim 11, wherein the deflectable member and over-centremechanisms are moulded as a one piece actuating section with moulded-inflexible hinges.
 13. A dose actuating mechanism according to claim 10,wherein first biasing means and second biasing means communicate withthe over-centre mechanisms.